Fire retardant acrylic polymers



United States Patent Ofiice 3,488,725 Patented Jan. 6, 1970 3,488,725FIRE RETARDANT ACRYLIC POLYMERS Allan Ellis Sherr, Martinsville, N.J.,and Walter Mpreland Thomas, Darien, -Conn., assiguors to AmericanCyanamid Company, Stamford, Conn., a corporation of Maine No Drawing.Continuation-impart of application Ser. No. 551,945, May 23, 1966. Thisapplication Aug. 2, 1968, Ser. No. 749,621

Int. Cl. 'C08f 45/56; C09k 3/28 U.S. Cl. 260-45.75 8 Claims ABSTRACT OFTHE DISCLOSURE Compositions of matter comprising an acrylic polymer andat least two compounds having the formula wherein X is chlorine, bromineor iodine useful in the production of structural members such as wallpaneling, are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of our copending application, Ser. No. 551,945,filed May 23, 1966 now abandoned.

BACKGROUND OF THE INVENTION The incorporation of various materials intothermoplastic resins in order to improve the flame-retardance thereofhas been known in the prior art. Many compounds are commerciallyavailable for such a use, among them being chlorostyrene copolymers,chlorinated parafiin wax in admixture with triphenyl stilbine,chlorinated paraflins and aliphatic antimonyl compounds, as well asantimony oxide-chlorinated hydrocarbon mixtures. A material drawback ofthese compounds, however, has been the fact that generally a largeamount, i.e., upwards of 35%, of additive must be incorporated into theresin in order to make it sufficiently flame-retardant. Also these priorart additives tend to crystallize or oil out of the resin after arelatively short time of incorporation.

SUMMARY We have now found a mixture of compound which may be added toacrylate and methacrylate polymers in relatively small amounts and stillresult in the production of satisfactory flame-retardant compositionsand which will not crystallize or oil out of the resin afterincorporation therein.

The production of acrylate and methacrylate composition which areflame-retardant, i.e., have high resistance to burning, is ofconsiderable commercial importance. For example, such. articles ascastings, moldings or laminated structures and the like are required, orat least desired, to be resistant to fire and flame and to possess theability to endure heat without deterioration. Typical illustrations ofsuch applications include structural members such as wall coverings,wall paneling, windows and items such a skylights, shower stalls, roomdividers and the like.

The exact mechanism by which the stannic halide mixture functions as aflame-retarding additive according to the instant invention is notcompletely understood. It is believed, however, while not wishing to bebound by any explanation or theory, that the stannic halides form acomplex with the acrylate or methacrylate polymer to create aflame-retarded system.

In addition to the resultant fiame-retardancy, we have also discoveredthat the use of a stannic halide mixture allows the addition of variousmaterials which, without the stannic halide, are insoluble in themonomer mixture before casting. Therefore, materials such as inorganicsalts which modify the electrical properties of the polymer can now beincorporated therein. Another surprising result in regard to the use ofthe stannic halide mixture is that the transparency or lighttransmission of the polymers is not inhibited after they have beenadded, a result which prohibits the use of many other knownflameretardants.

Furthermore, we have observed that the use of the stannic halidemixtures does not decrease the other desired properties of the polymers,such as hardness, and in some instances, these properties are actuallyalso enhanced.

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS Theacrylate and methacrylate polymers into which the flame-retardant agentsmay be incorporated to produce the novel compositions of the presentinvention, are the acrylate and methacrylate polymers produced frommonomers having the formula wherein R is hydrogen or methyl radical andR is hydrogen or an alkyl radical having from 1 to 6 carbon atoms,inclusive. Examples of monomers represented by Formula I include acrylicacid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropylacrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-amylacrylate, t-amyl acrylate, hexyl acrylate and the corresponding methyl,ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, n-amyl, t-amyland hexyl methacrylates.

The acrylate and methacrylate polymers may be uti lized as homopolyrnersor copolymers thereof in amounts such that the final polymers contain atleast 30%, by weight, based on the total weight of the polymer, of theacrylate, methacrylate or mixture thereof.

Examples of monomers which can be copolymized with the monomersrepresented in Formula I, either singly or in a plurality (two, three,four or any desired number), the latter often being desirable in orderto improve the compatibility and copolymerization characteristics of themixture of monomers and to obtain copolymers having the particularproperties desired for the particular service application, in amounts upto about 70%, by weight, based on the total weight of the polymer, aresuch monomers as the unsaturated alcohol esters, more particularly theallyl, methallyl, vinyl, etc., esters of saturated and unsaturatedaliphatic and aromatic monobasic and polybasic acids such, for instance,as acetic, propionic, butyric malonic, succinic, maleic, fumaric,citraconic, itaconic, benzoic, phthalic, terephthalic, etc., acids; thesaturated monohydric alcohol esters, e.g., the methyl, ethyl, propyl,isopropyl, butyl, sec-butyl, amyl, etc., esters of ethylenicallyunsaturated aliphatic monobasic and polybasic acids, illustrativeexamples of which appear above; vinyl cyclic compounds (includingmonovinyl aromatic hydrocarbons, e.g., styrene, 0-, m-, andp-chlorostyrenes, -bromostyrenes, -fluorostyrenes, -rnethylstyrenes,-ethylstyrenes, -cyanostyrenes, the various poly-substituted styrenessuch, for example, as the various di-, tri-, and tetra-chlorostyrenes,-bromostyrenes, -fluorostyrenes, -methylstyrenes, -ethylstyrenes,-cyanostyrenes, etc., vinyl naphthalene, vinylcyclohexane, vinyl furane,vinyl pyridine, vinyl dibenzofuran, divinyl benzene, trivinyl benzene,allyl benzene, diallyl benzene, N-vinyl car'bazole, the various allylcyanostyrenes, the various alpha-substituted styrenes andalpha-substituted ring-substituted styrenes, e.g., alphamethyl styrene,alpha-methyl-para-methyl styrene, etc.

Other examples of monomers that can be copolymerized with the monomersof Formula I are the vinyl halides, more particularly vinyl fluoride,vinyl chloride,

.4 erably from about 10% to about 20%, by weight, of the mixture, basedon the weight of the polymer.

The method of incorporating the stannic halide mixture into the polymersis not critical and any known method may be used. One method is to addthe halide mixture vinyl bromide and vinyl iodide, and the variousvinylidene during the polymer production, i.e. during thepolymerizacompounds, including the vinylidene halides, e.g., vinyltion(casting etc.). The halide mixture may also be added idene chloride,vinylidene bromide, vinylidene fluoride, to a solvent solution of thepolymer, which solvent is vinylidene iodide and the like. then removedby evaporation, etc. Additionally, the More specific examples of allylcompounds that can halide mixture may be added to the polymer by 1) becopolymerized with the allyl compounds of Formula molding or extrudingthem simultaneously, (2) milling I are allyl alcohol, methallyl alcohol,diallyl carbonate, them on, for example, a two-roll mill, a Banburymixer allyl lactate, allyl ot-hydroxyisobutyrate, allyl trichloroetc.,or (3) by merely blending the halide mixture with silane, diallyldiglycol carbonate, diallyl methylgluconate, the polymer in powder form.dially tartronate, diallyl tartrate, diallyl mesaconate, the It shouldbe noted that it is also within the scope of diallyl ester of muconicacid, diallyl chlorophthalate, the present invention to incorporate suchingredients as diallyl dichlorosilane, the diallyl ester ofendomethylene plasticizers, dyes, pigments, stabilizers, antioxidants,antitetrahydrophthalic anhydride, triallyl tricarballylate, tristaticagents, photochromic materials and the like to our allyl cyanurate,triallyl isocyanurate, triallyl citrate, trinovel compositions. allylphosphate, tetrallyl silane, tetrallyl silicate, hexallyl The followingexamples are set forth for purposes of disiloxane, etc. Other examplesof allyl compounds that illustration only and are not to be construed aslimitations may be employed are given, for example in US. Patent on thepresent invention except as set forth in the ap- -No. 2,510,503, issuedJune 6, 1950. pended claims. All parts and percentages are by weightAmong the comonomers which are preferred for use unless otherwisespecified. in carrying our invention into eflFect are, for example, Anyappropriate flame-retardance test may be used to compounds such asacrylonitrile, the various substituted determine the flame-retardingproperties of any specific acrylonitriles (e.g., methacrylonitrile,ethacrylonitrile, compound. One test which is reasonably efiicient isASTM phenylacrylonitrile, etc.) acrylamide and the various N- testD635-63. The specifications for this test are: a substituted acrylamidesand alkacrylamides, for instance, specimen, 5" in length, 0.5" in widthand 0.125 in N-dialkyl acrylamides and methacrylamides, e.g., N-thickness, is marked at the 1" and 4" lengths and is then dimethyl,-diethyl, -dipropyl, -dibutyl, etc., acrylamides supported with itslongitudinal axis horizontal and its and methacrylamides. Also theglycol diacrylates, i.e. transverse axis inclined at 45 to thehorizontal. A Bunsen those compounds produced by esterifying acrylic ormethburner with a 1" blue flame isplaced under the free end acrylic acidwith a polyglycol having 4-8 carbon atoms of the strip and is adjustedso that the flame tip is just or a monoglycol having 2-4 carbon atoms.Examples of in contact with the strip. At the end of 30 seconds, thethese glycols include diethylene glycol, triethylene glycol, flame isremoved and the specimen is allowed to burn. tetraethylene glycol,dipropylene glycol, bis(4-hydroxy- If the specimen does not continue toburn after the first butyDether, polyethylene glycol, ethylene glycol,proignition it is immediately recontacted with the burner py leneglycol, the propanediols, 1,2 and 1,3; the butanefor another 30secondperiod. If, after the two burnings, diols, 1,2, 1,3 and 1,4 and thelike. the strip is not burned to the 4" mark, the specimen is Of course,it is also possible to utilize copolymers designated asself-extinguishing or flame-retardant. produced from two or more of themonomers represented An alt r a t 8 0 m film 0f a ut 0.1 5" by FormulaI, above and still obtain the benefits heretoin tTJiCkIleSS and Place aburning match in Contact therafore set forth. with. If the filmcontinues to burn after the match is The above mentioned monomers may bepolymerized, removed, the film is not -P copolymerized, etc., in anyknown manner such as by free-radical generating catalysts, irradiation,anion and/ or Example 1 1 3 P catalysts and the 11146, the Specificmethod of To 30 parts of methyl methacrylate are added 5 parts 13 y ghowever, formmg 110 p of the present of $1101, and 5 parts of S1'1I4.The mixture is stirred until mventlonthe halides dissolve and then partsof a solids The stannic halide mixture should be mcorporated, solutionof poly(methyl methacrylate) in methyl methslngly or m adm1xture, intothe polymers in flame-retardacrylate are added. The resultant mixture isstirred until mg amounts, e.g. at least about 8%, by weight, andprefhomogeneous and 0.8 part of benzoyl peroxide is then TABLE I Resultsof ASTMD63563 Polymer Halide mixture, percent Test Example:

1 P01y(methyl methacrylate) 811014, 5 plus SnI4, 5 Self-extinguishing. g58 815013010 1311131118. 4 "III::ziblhetliviiuetitarylatbl:IIIIIIIIIIIIIIIIII SuC l 4, s'pitiss'riizSelf-girtlnguishing, 5 do 81101 1 Burns. 5 do SnBn, 10 o. 7 .do SnBn, 4plus Sub, 4. Self-extinguishing. R .rlo SnI4, 8 Burns. 9 F013; (methylmethacrylate) SnBrt, 4 plus 811014, 4. Self-extinguishing,

B Selieitinguishing. Burns. Do.

Self-extinguishing. Burns. 16--- snon, Do. 17--. Methylmethacrylate/styrene, /5..- SnBn, 4 plus S1114, 6 Self-extinguishing. 18Poly(ethy1 acrylate) SnCh, 10 plus SnBn, 10.- Do. 19.. Methylmethacrylate/aerylonitrile, 60/40. SnOh, 7 plus SnIt, 5.-.. D0. 20Methyl methacrylate/vinyl acetate, 92/8 SnClt, 7 plus Snh, 5.... Do. 21Poly (n-hexyl aerylate) 811014, 6 plus SnBn, 6.- Do. 22 Poly(acryl1cacid) SnBn, 7.5 plus Snh, 7.5 Do. Poly(methy1 methacrylate) SnCh, 3 plusSnBn, 2 plus SnI4, 3.. D0.

added. The system is stirred until the peroxide is dissolved and theresultant solution is charged into a polymerization cell. The cell isheated at 55 C. for 16 hours, 70 C. for 1 hour and 100 C. for 1 hour. Acast sheet is then recovered and subjected to the ASTM-D63563 fiame testspecified above. The sheet is self-extinguishing.

Following the procedure of Example 1 various other acrylate andmethacrylate polymers were formed containing various additives. Theresults are set forth in preceding Table I.

In each of Examples 17-23 the halides, when added to the same polymerindividually at the combined concentration, did not produce aself-extinguishing polymer.

We claim:

1. A flame-retarded composition comprising a polymer of a monomer havingthe formula wherein R is selected from the group consisting of hydrogenand a methyl radical and R is selected from the group consisting ofhydrogen and an alkyl radical having from l-6 carbon atoms, inclusive,and a flame-retarding amount of a mixture of at least two compoundshaving the formula SnX wherein X is selected from the group consistingof chlorine, bromine and iodine, in an amount of from 8% to 20% based onthe weight of the polymer, the sum of the amounts of said compoundsbeing less than that amount at which any of said compounds usedfunctions individually in a flame-retarding manner similar to saidmixture in the same polymer to which the mixture is added.

2. A composition according to claim 1 wherein said polymer contains upto 70%, by weight, based on the total Weight of the polymer, of at leastone ethylenically unsaturated monomer copolymerizable therewith.

3. A composition according to claim 1 wherein said polymer ispoly(methyl methacrylate).

4. A composition according to claim 1 wherein said polymer is a coplymerof methyl methacrylate and acrylonitrile.

5. A composition according to claim 1 wherein said polymer is acopolymer of methyl methacrylate, acrylonitrile and acrylamide.

6. A composition according to claim 1 wherein said additive is a mixtureof stannic iodide and stannic chloride.

7. A composition according to claim 1 wherein said additive is a mixtureof stannic iodide and stannic bromide.

8. A composition according to claim 1 wherein said additive is a mixtureof stannic chloride and stannic bromide.

References Cited UNITED STATES PATENTS 3,239,482 3/1966 Rapp 260-41DONALD E. CZAIA, Primary Examiner J. P. HOKE, Assistant Examiner US. Cl.X-R. 2528. l

